Does your 'friend' know this person or in any sort of wider community context and likely come accross them again?
In an ideal world, I'd report but would worry slightly about the ramifications if I actually knew the person.
Just remember racism is a hate crime and is illegal. I'd be anonymously tipping off the old bill online but not at the cost of my life becoming difficult because of it.
Does your 'friend' know this person or in any sort of wider community context and likely come accross them again?
In an ideal world, I'd report but would worry slightly about the ramifications if I actually knew the person.